Abstract

Untreated and nitrogen-treated amorphous hydrocarbon layers (a-C:H) were produced by plasma supported chemical discharge from the gas phase (PACVD). Some of the untreated probes were later modified through implantation with nitrogen ions. The layers were examined by optical spectroscopy and measurements on conductability and photo-conductability. At room temperature conductability was recorded in the range of 1.0 E-13 to 1.0 E-5/ohm.cm for untreated films, 1.0 E-11 to 1.0 E-4/ohm.cm for nitrogen treated ones, and 1.0 E-8 to 1.0 E-2/ohm.cm for ion-implanted ones. Measurements of the temperature dependence of the electrical conductability provide information on the mechanisms of conduction. Measurements at temperatures between 100 and 300 K mostly yielded values around 0.3, which points to an overlaying of several mechanisms. Measurements of photoconductability show that its contribution only dominates at temperatures under approx. 100 K. From optical absorption spectra Tauc gaps were calculated which, with an increasing nitrogen content, decrease from 0.9 eV to under 0.2 eV. The results are comparable to ion-implanted layers and layers treated during production.